1. GPL Photonics Laboratory, State Key Laboratory of Luminescence and Applications, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, China
2. Department of Physics, Faculty of Science, University of Fayoum, Fayoum 63514, Egypt
3. Lightwave Communications Research Group, Department of Electrical and Computer Engineering, School of Engineering, Democritus University of Thrace, 67100 Xanthi, Greece
4. Department of Aerospace Science and Technology, National Kapodistrian University of Athens, 34400 Psahna Evias, Greece
5. The Institute of Optics, University of Rochester, Rochester, NY 14627, USA